The present invention relates in general to automotive heating, ventilating, and air conditioning (HVAC) systems, and, more specifically, to tailored flow patterns of moving air in an HVAC system.
Some of the register vents in automotive vehicles supplying conditioned air from one or more air handling units (AHU) can be manually adjusted in order to aim the air at specific body areas. In particular, register vents on the instrument panel are usually of this type. Other registers such as floor registers and window defrost registers are not typically adjustable. Although the user has some capability to customize the airflow pattern, the conventional arrangements have achieved only limited capacity to customize the flow. For example, not all desired areas may be covered within the adjustability range of the adjustable vents. Directing air toward one area may mean that it is taken away from another area where is it also desired. It becomes difficult to control the amount of conditioned air directed to body areas not within the direct circulation from the aimed vents, so that some body areas may become too warm or cold at the expense of other body areas. On the other hand, conventional systems have limited ability to reduce airflow to areas where it may not be needed. Manually closing off a register vent supplying an area where it is not needed may be inconvenient or impossible during driving.
When the HVAC system operates in recirculation mode, interior air is directed back into the blower of the AHU instead of fresh, outside air. Conventionally, the interior air is captured at the front passenger footwell. The resulting air circulation fails to provide full thermal conditioning of occupants who are not directly impinged by air flowing from a register. With the return flow being picked up in the front passenger footwell, the recirculated air passing into the rear seating area or to critical areas for a driver or front passenger (e.g., top of head, pelvis, etc) is limited. The neglect of rear seat occupants may be especially undesirable in some circumstances such as in chauffeured vehicles with paying passengers in the back of the vehicle. Moreover, occupant comfort is better served when air is supplied at a low or diffuse flow. Thus, it would be desirable to avoid the necessity of high speed, directional flows to achieve any desired heating or cooling effect—but it is difficult for diffuse flow or low velocity flow to provide a tailored experience for an individual occupant since the diffuse air pattern is typically non-directional.
In order to produce thermal comfort, HVAC systems have often been oversized in order to provide heating or cooling to the occupant as quickly as possible, with limited regard to the impact on system efficiency or vehicle fuel economy. This trade-off is becoming less desirable as vehicle efficiency becomes more critical in buyer decisions. Thus, it would be desirable to achieve improved efficiency while providing increased passenger comfort.